ELECTRICITY STORAGE TO COVER WIND-SOLAR LULLS AND SEASONAL VARIATIONS

- Whereas, the turnkey capital costs of battery systems likely would be about 50% less over the next decade, that storage approach would never be cheap enough to accommodate the big seasonal shifts in renewable power production.

- Battery systems could prove viable for storing solar electricity produced during midday hours for use during late afternoon/early evening hours, and “maybe” for up to a week later, but not over seasonal time­frames.

- New technologies are needed to convert “low-cost” renewable energy into chemical fuel whenever excess solar and wind electricity is available. Low-cost hydrogen from renewables, stored underground, may become an economically feasible approach. See note.

- Fuel cells hold more promise for urban power storage, particularly those based on liquid hydrocarbons. However, whereas technically feasible, they are not economical at present.

NOTE: One approach would be to produce electricity with base-loaded nuclear plants, and produce hydrogen with electricity and store it in underground caverns all over the world. This would need to apply to at least 70 - 80% of total primary energy, not just the 40% used for producing electricity.

Examples of Electricity Storage to Cover Seasonal Variations

For those of you who may have illusions/fantasies of 100% RE for electricity*, here are some examples of storage capacities needed to ensure 24/7/365 electricity service, year after year.

* Energy for services other than electricity, such as transportation, space heating/cooling, industrial processes, etc., is a separate issue.

There cannot be heavy penetration of wind and solar electricity without storage and standby generation because the sum of wind and solar may be simultaneously near zero, especially in winter with snow and ice on the PV panels, i.e., PFB functions by the other generators are needed 24/7/365. Those functions:

- Cannot be performed by wind and solar.

- Can be performed by large-scale hydro storage, which is the lowest cost option, by far.

- Can be performed by battery systems, but that would be very expensive, even if battery system cost became 50% less. See above Dr. Chu’s comments and URLs.

The euanmearns URLs show the type of analysis required to determine seasonal storage capacities:

California

1) The seasonal storage would need to be capable to provide about 20 TWh delivered as AC.

- Such a high solar percentage would generate a large surplus of electricity during midday hours that would need to be stored for later use.

- Battery storage would provide mainly diurnal storage, which agrees with Dr. Chu’s comments, and stored gas, such as hydrogen produced with renewable energy, would provide the rest of the storage. See Appendix 5.

- US and CA electricity is about 37.5% greater in 2050 than in 2015, due to (heat pumps + plug-ins - increased efficiency). See table 1.

The seasonal storage would need to be capable to provide about 50 TWh delivered as AC to balance ERCOT’s wind and solar generation against ERCOT’s demand over the three-year period considered in this 100% renewable scenario.

The windtaskforce URLs show the type of analysis required to determine wind/solar lull storage capacities:

Germany

The storage systems would need to be capable to provide about (100-h lull + 50-h lull) x 62.0 GW = 9300 GWh = 9.3 TWh delivered as AC. Imports and exports would be minimal, as nearby countries also would have wind and solar lulls. See note.

NOTE: Regarding battery systems for utilities, it is entirely reasonable to assume some percent of the installed capacity would be out of service due to scheduled and unscheduled outages.

APPENDIX 1

Fossil Fraction of World Primary Energy Consumption Unchanged for 43 Years

In the 1970s, the big worry was fossil fuels would soon run out, and so we should “use them wisely”. But in the 1980s, the risk changed to one of an overheating planet, and so we should not use them at all. This article shows unchanged fossil energy use from 1970 to 2013, a period of 43 years.

Here is a table of world primary energy consumption percentages (fuels, electricity, etc.) during the 2011 - 2015 period, which, indicates hardly any progress towards RE, despite worldwide investments in renewables of $250 - $300 billion in each of these 5 years. The fossil fuel percentage likely remained about the same in 2016 and 2017. Table 1 shows the data for the years 2011 - 2015, a 5-y period.

If at some future date, Vermont were to use 75% homegrown and out of state wind and solar, with the rest from home-grown and imported hydro, etc., two consecutive, 4-day wind/solar lulls, a common occurrence in winter, would require 2 x 4 x 0.75 x 16,712 = 100,272 MWh delivered as AC from storage, at a turnkey capital cost of 100272 x 1000 x 250 = $25 billion, at $250/kWh delivered as AC.

That is just for 40% of the primary energy used for generating electricity. The other 60% of PE is a separate issue.

Some 100% RE folks want Vermont to be "energy independent" (disconnect from the NE grid?) and to stop using fossil fuels (coal, oil, gas) and nuclear by 2050.

3) Provides stability to the grid, during times other generators are started in the event of sudden drops in wind or other network issues.

Here is an aerial photo of the system on a 10-acre site. The installed cost of the Australian Powerpack system was about $66 million, or 66 million/129,000 = $512/kWh; this is a low price, because Tesla was eager to obtain the contract.

NOTE: The battery does not serve to store electricity for delivery at a later hour on the same day, or a week later, or several months later. For those purposes, much larger batteries would be required.

APPENDIX 5

California has access to hydro storage and concentrated solar power, CSP, storage, which have a much lower cost, $/kWh, than battery storage at about $250/kWh delivered as AC.

The above analysis is based on extrapolating from existing conditions. The rate of change of those conditions, on an absolute basis, is very slow, even in California. Somewhat like turning around a loaded supertanker.

- The fact a growing duck curve exists in California indicates a much greater level of RE efforts are required to offset it.

- The high costs of the present level of RE efforts has caused California residential rates to increase, as happened in other RE countries, such as Denmark and Germany.

- A similar duck curve is starting to emerge in New England, albeit only on rare sunny days.

California residential rates increased from 14.2 c/kWh, at start 2008 to 15.4 c/kWh, at end 2015, up 12% since 2008

US residential rates decreased from 10.8 c/kWh, at start 2008 to 10.4 c/kWh, at end 2015, down 3% since 2008

Ideally, all residential and other buildings should be energy-surplus buildings, with:

1) Highly insulated and sealed.

2) Energy efficient systems and lighting.

3) Heat pumps for space heating and cooling and hot water.

4) Battery systems; store PV solar during midday, use in the evening

5) Thermal storage systems; store PV solar, use as needed

6) PV solar systems.

Such buildings would:

1) Take a long time to warm up or cool down, i.e., the internal temperature would vary just a few degrees during a day, even though the outside temperature would vary 30 degrees or more.

2) Use minimal energy for heating, cooling and electricity (Btu/ft2/y)

3) Have enough electricity left over to charge plug-in vehicles at night.

Such a setup would greatly reduce the daily variation in electrical demand, and thus reduce the need for generating capacity, MW.

However, almost all of the building stock is very far from highly insulated and sealed, etc.: they are energy-hog buildings. Placing solar panels on the roofs of such buildings makes for good visuals, but creates grid disturbing duck curves, especially in California.

APPENDIX 7

Norway Electricity Generating System

Norway electricity generation was about 149 TWh in 2016, about 143.4 TWh, or 96.3% from reservoir hydro plants and run of river hydro plants. Norway total hydro reservoir capacity is 84.3 TWh.

All those plants are connected to the high voltage network. Modulating the water flows through the turbines performs the peaking, filling-in and balancing, PFB, functions.

The combined storage reservoirs act as a giant battery that is continuously charged with rainwater and runoff and discharges water through turbines, as needed to meet electricity demand 24/7/365, year after year.

The HV networks of Denmark, Germany and the Netherlands are connected to the HV network of Norway with HVDC lines. During periods of higher winds, electricity (usually at near-zero or negative wholesale prices) is sent via these lines to Norway, which merely reduces the water flow through the turbines.

Norway uses the “saved” water to generate electricity when wholesale prices are high, such as during wind and solar lulls and higher demands. Germany would like to send its excess electricity from North Germany to South Germany but HVDC lines, already 15 years overdue, do not exist, mostly due to NIMBY concerns.

Quebec Electricity Generating System

Quebec electricity, generated and purchased, was about 217 TWh in 2016, of which about 172 TWh/y from 36911 MW of 63 large hydro plants.

- Run of river, 35 plants, capacity 10068 MW, production about 47.3 TWh in 2016

The active water storage of the reservoir plants is about 1/3 of total storage. The active storage is equivalent to about 176 TWh/y, about equal to Quebec’s annual electricity requirements.

The active storage could generate another 176 - 124.7 = 51.3 TWh/y, however, this is dependent on environmental impacts, recreation, water levels, flow rates, navigation, flood control, and the weather.

All plants are connected to the high voltage network. Modulating the water flows through the turbines performs PFB functions.

The combined storage reservoirs act as a giant battery that is continuously charged with rainwater and runoff and discharges water through turbines, as needed to meet electricity demand 24/7/365, year after year.

In 2016, Quebec total net exports were 32.6 TWh, of which 20.8 TWh, directly or indirectly, to New England (per ISO-NE) and 11.8 TWh to other states, such as New York State. Revenues were $1.568 billion; average sales prices 4.8 c/kWh.

Modulating the outputs of the gas turbines, which requires more Btu/kWh and emits more CO2/kWh, performs most of the PFB functions. The modulating would increase as more wind and solar is added to the system.

NE wholesale prices have averaged about 4.5 to 5 c/kWh since 2009. Closing down gas, nuclear, coal (all of which generate at less than 5 c/kWh), and oil plants, would create a huge generation deficiency that likely would need to be offset mostly by increased build outs of wind, solar, refuse, hydro, plus increased imports via tie lines, plus large-scale storage systems. The PFB functions would be performed by storage systems to accommodate the variability and intermittency of wind and solar.

California has made major efforts to implement electricity generation from renewables, such as wind and solar. Wind and solar electricity is more expensive than fossil and hydro electricity, due to the costs of:

- Increased ramping up by traditional generators. As solar disappears in the late afternoon and demand is ramping up, generation by traditional sources has to ramp up as well; the more solar, the steeper the ramp up, MW/h.

- Increased demand management to shift demand from late afternoon/early evening to after 11 PM.

As a result of those costs, California electric rates have increased much faster than US rates.

In 2011, California rates were 35% higher than US rates. In 2017, they were 60% higher than US rates, a clear sign increased RE leads to increased electric rates. The same is true in Germany and Denmark, which have high RE percentages. Denying it is beyond rational. Source EIA website. See table.

Year

California

US

CA higher than US

c/kWh

c/kWh

%

2011

13.1

9.7

35

2012

13.5

9.6

41

2013

14.3

9.8

46

2014

15.2

10.1

50

2015

15.4

10.0

54

2016

15.3

9.9

55

2017

16.2

10.1

60

California, and other states, should concentrate on energy surplus housing and other buildings.

Over a 24-h period, their indoor temperature would vary a few degrees F, with outdoor temperatures varying 30F or more.

They would have solar systems and batteries and have enough electricity to charge plug-in hybrids at night.

With lower solar and battery prices, that would be the most rational approach to make disappear most of the DUCK curves.

Hannah Pingree on the Maine expedited wind law

Hannah Pingree - Director of Maine's Office of Innovation and the Future

"Once the committee passed the wind energy bill on to the full House and Senate, lawmakers there didn’t even debate it. They passed it unanimously and with no discussion. House Majority Leader Hannah Pingree, a Democrat from North Haven, says legislators probably didn’t know how many turbines would be constructed in Maine."

Maine Center For Public Interest Reporting – Three Part Series: A CRITICAL LOOK AT MAINE’S WIND ACT

******** IF LINKS BELOW DON'T WORK, GOOGLE THEM*********

(excerpts) From Part 1 – On Maine’s Wind Law “Once the committee passed the wind energy bill on to the full House and Senate, lawmakers there didn’t even debate it. They passed it unanimously and with no discussion. House Majority Leader Hannah Pingree, a Democrat from North Haven, says legislators probably didn’t know how many turbines would be constructed in Maine if the law’s goals were met." . – Maine Center for Public Interest Reporting, August 2010 https://www.pinetreewatchdog.org/wind-power-bandwagon-hits-bumps-in-the-road-3/From Part 2 – On Wind and Oil Yet using wind energy doesn’t lower dependence on imported foreign oil. That’s because the majority of imported oil in Maine is used for heating and transportation. And switching our dependence from foreign oil to Maine-produced electricity isn’t likely to happen very soon, says Bartlett. “Right now, people can’t switch to electric cars and heating – if they did, we’d be in trouble.” So was one of the fundamental premises of the task force false, or at least misleading?" https://www.pinetreewatchdog.org/wind-swept-task-force-set-the-rules/From Part 3 – On Wind-Required New Transmission Lines Finally, the building of enormous, high-voltage transmission lines that the regional electricity system operator says are required to move substantial amounts of wind power to markets south of Maine was never even discussed by the task force – an omission that Mills said will come to haunt the state.“If you try to put 2,500 or 3,000 megawatts in northern or eastern Maine – oh, my god, try to build the transmission!” said Mills. “It’s not just the towers, it’s the lines – that’s when I begin to think that the goal is a little farfetched.” https://www.pinetreewatchdog.org/flaws-in-bill-like-skating-with-dull-skates/

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